Imaging apparatus including unit pixel, counter electrode, photoelectric conversion layer, and voltage supply circuit
An imaging apparatus includes a unit pixel including a pixel electrode, a charge accumulation region electrically connected to the pixel electrode, and a signal detection circuit electrically connected to the charge accumulation region; a counter electrode facing the pixel electrode; a photoelectric conversion layer disposed between the electrodes; and a voltage supply circuit configured to selectively apply any one of first, second, and third voltages between the electrodes. The photoelectric conversion layer exhibits first and second wavelength sensitivity characteristics in a wavelength range when the voltage supply circuit applies the first and second voltages between the electrodes, respectively, and becomes insensitive to light in the wavelength range when the voltage supply circuit applies the third voltage between the electrodes.
1. An imaging apparatus comprising:
a unit pixel including
a pixel electrode,
a charge accumulation region electrically connected to the pixel electrode, and
a signal detection circuit electrically connected to the charge accumulation region;
a counter electrode facing the pixel electrode;
a photoelectric conversion layer disposed between the pixel electrode and the counter electrode, the photoelectric conversion layer converting light incident on the photoelectric conversion layer into charge carriers; and
a voltage supply circuit configured to selectively apply any one of a first voltage, a second voltage, and a third voltage between the pixel electrode and the counter electrode, wherein:
the charge carriers are accumulated at the charge accumulation region,
the photoelectric conversion layer exhibits a first wavelength sensitivity characteristic in a wavelength range when the voltage supply circuit applies the first voltage between the pixel electrode and the counter electrode,
the photoelectric conversion layer exhibits a second wavelength sensitivity characteristic in the wavelength range when the voltage supply circuit applies the second voltage between the pixel electrode and the counter electrode, the second wavelength sensitivity characteristic being different from the first wavelength sensitivity characteristic,
the photoelectric conversion layer becomes insensitive to light having a wavelength in the wavelength range when the voltage supply circuit applies the third voltage between the pixel electrode and the counter electrode, and
the voltage supply circuit applies the third voltage between the pixel electrode and the counter electrode during at least a part of a period in which the voltage supply circuit changes a voltage applied between the pixel electrode and the counter electrode from the first voltage to the second voltage or from the second voltage to the first voltage.
2. The imaging apparatus according to claim 1 ,
wherein the at least a part of the period is a readout period in which a potential of the charge accumulation region is read.
3. The imaging apparatus according to claim 1 , wherein:
the first wavelength sensitivity characteristic is a characteristic of having a sensitivity equal to or higher than a first value in a visible region and having a sensitivity equal to or higher than a second value in a infrared region, and
the second wavelength sensitivity characteristic is a characteristic of having a sensitivity equal to or higher than a third value only in the visible region.
4. The imaging apparatus according to claim 1 ,
wherein the voltage supply circuit applies the first voltage and the second voltage, in an alternating manner, between the pixel electrode and the counter electrode.
5. The imaging apparatus according to claim 1 ,
wherein the voltage supply circuit changes the voltage applied between the pixel electrode and the counter electrode between the first voltage and the second voltage at intervals of frames.
6. The imaging apparatus according to claim 1 ,
wherein the voltage supply circuit changes the voltage applied between the pixel electrode and the counter electrode between the first voltage and the second voltage at a certain frequency.
7. The imaging apparatus according to claim 1 ,
wherein the photoelectric conversion layer includes photoelectric conversion films.
8. The imaging apparatus according to claim 7 ,
wherein at least one of the photoelectric conversion films includes an organic material.